Contao is an Open Source CMS. In versions starting from 5.0.0 and prior to 5.3.38 and 5.6.1, the table access voter in the back end doesn't check if a user is allowed to access the corresponding module. This issue has been patched in versions 5.3.38 and 5.6.1. A workaround involves not relying solely on the voter and additionally to check USER_CAN_ACCESS_MODULE.
Contao is an Open Source CMS. In versions starting from 5.3.0 and prior to 5.3.38 and 5.6.1, under certain conditions, back end users may be able to edit fields of pages and articles without having the necessary permissions. This issue has been patched in versions 5.3.38 and 5.6.1. There are no workarounds.